Tick salivary gland extract-activated transmission of Borrelia afzelii spirochaetes

Saliva-activated transmission of Borrelia afzelii Canica, Nato, du Merle, Mazie, Baranton et Postic, 1993 was demonstrated using salivary gland extract (SGE) from Ixodes ricinus (L., 1758) ticks and C3H mice. Injection of Borrelia spirochaetes together with SGE increased the level of bacteraemia and accelerated the appearance of bacteria in the urinary bladder, compared with the injection of spirochaetes alone. More I. ricinus nymphs became infected when feeding on mice inoculated with B. afzelii plus SGE. Analysis of cytokines produced by cells of draining lymph nodes from SGE-treated mice showed a suppression of proinflammatory cytokines IFN-gamma, IL-6 and GM-CSF following a transient upregulation in comparison with the control mice infected without SGE.     

Studies on the transovarial transmission of Borrelia burgdorferi sensu lato in the taiga tick Ixodes persulcatus

The possibility of vertical transmission of Borrelia burgdorferi sensu lato in Ixodes persulcatus Schulze, 1930 ticks was studied in the progeny of 20 females collected from the vegetation in an active focus of ixodid tick-borne borrelioses (ITBB) located in the Perm oblast, Russia, where Borrelia garinii and B. afzelii are circulating. The presence of Borrelia DNA was detected by the PCR method after feeding and egg laying in 16 engorged females (80.0%), as well as in 36.5 +/- 7.2% samples containing 20 eggs each and in 21.4 +/- 4.2% samples containing 10 eggs each. The respective rates of individual egg infection were 0.4-8.0% and 0.5-23.0%. PCR analysis of 370 eggs (one egg per sample) and 781 unfed larvae hatched from the same egg masses (1, 10, 20, 40, and 50 larvae per sample) failed to reveal the presence of Borrelia DNA. Negative results were also obtained in experiments on inoculating the BSK II medium with the egg and larval materials. Microscopic analysis of 1,683 smear preparations of eggs and 1,416 preparations of unfed daughter larvae revealed spirochete-like cells in 7 (0.4 +/- 0.3%) and 13 (0.9 +/- 0.5%) preparations, respectively; typical Borrelia cells were found in seven preparations of larvae (0.5 +/- 0.4%). Only 1 out of 16 infected females transmitted Borrelia vertically, through the eggs to the larval progeny. The infection rate in this progeny was about 7%, and the prevalence of Borrelia in individual larvae was 0.4-0.8 cells per 100 microscopic fields. These data do not allow the conclusion that transovarial transmission of B. burgdorferi sensu lato in the I. persulcatus tick is an established fact. However, they show that, even if such transmission is possible, its probability is very low.     

Lyme borreliosis: insights into tick-/host-borrelia relations

Lyme borreliosis (LB) is a serious infectious disease of humans and some domestic animals in temperate regions of the Northern Hemisphere. It is caused by certain spirochetes in the Borrelia burgdorferi sensu lato (s.l.) species complex. The complex consists of 11 species (genospecies). Borrelia burgdorferi sensu stricto (s.s.), Borrelia garinii and Borrelia afzelii are the major agents of human disease. Borrelia burgdorferi s.l. species are transmitted mainly by ticks belonging to the Ixodes ricinus species complex plus a few additional species not currently assigned to the complex. B. burgdorferi infections may produce an acute or chronic disease with a wide array of clinical symptoms such as erythema migrans (EM), carditis, arthritis, neuroborreliosis, and acrodermatitis chronica atrophicans (ACA). Differences in LB spirochetes 'genospecies' and strains/isolates determine the occurrence and severity of this multi-system disease. Accurate and reliable identification of the LB spirochetes in ticks as well as knowledge of their prevalence are essential for prevention against the disease and development of an effective vaccine. An overview of the knowledge of molecular factors with emphasis on potential protein-carbohydrate interactions in the tick-borrelia system is the main focus of this review.     

Effect of salivary gland extract from Ixodes ricinus ticks on the proliferation of Borrelia burgdorferi sensu stricto in vivo

Saliva-activated transmission (SAT) of Borrelia burgdorferi sensu stricto was demonstrated using real-time PCR and salivary gland extract (SGE) from partially fed Ixodes ricinus ticks. C3H/HeN mice were injected intradermally with 1.5 x 10(3) spirochetes mixed with 40 microg of SGE per mouse. The control group was inoculated with the same dose of spirochetes without SGE. The accelerating effect of SGE on spirochete proliferation was demonstrated on day 1 post infection, when a 4.2-fold increase in spirochetes was found in the skin and a 10-fold increase in the blood, compared with control mice. The data represent the first direct evidence of a SAT effect of I. ricinus SGE on infection with the Lyme disease agent B. burgdorferi.     

Effect of tick salivary gland extract on the cytokine production by mouse epidermal cells

Previous studies have demonstrated that both tick saliva and Borrelia burgdorferi sensu lato antigens modulate the cytokine response of the host. In this paper, the effect of salivary gland extract (SGE) from Ixodes ricinus (L., 1758) ticks on cytokine production by primary cultures of mouse epidermal cells stimulated with Borrelia afzelii Canica, Nato, du Merle, Mazie, Baranton et Postic, 1993 spirochetes was analysed. Epidermal cells were derived from C3H/HeN mice, susceptible to Lyme disease, and BALB/c mice, which are resistant. In cultures from C3H/HeN mice, SGE down regulated production of tumour necrosis factor alpha (TNF-alpha) and up regulated Th2 cytokine, interleukin 4 (IL-4). Cultures from BALB/c mice produced higher basal levels of monitored cytokines, but their production was affected by SGE a different way. While Th2 cytokines IL-6 and IL-10 were down regulated, the effect on TNF-alpha and IL-4 was ambiguous. These results indicate that the effect of tick saliva on the epidermal cells of Lyme disease-susceptible C3H/HeN mice mirrors its effect on other cells of the immune system.     

Prevalence of borreliae in Ixodes ricinus ticks from southern Moravia, Czechoslovakia

A total of 378 adult Ixodes ricinus ticks were collected by flagging vegetation in four localities of two districts (Breclav, Znojmo) in south Moravia and examined microscopically. Borreliae were identified in Giemsa-stained midgut smears from 32 (i.e. 8.5%) ticks (9.4% females, 7.2% males); the infection rate varied between 0.0 and 11.4% in the four localities examined. Among female ticks, significantly more were found to be infected in autumn (19.7%) than in spring (5.8%). Dark-field (DF) and Giemsa-stained smears (GS) examinations were compared for their sensitivity in detecting borreliae in 128 field-collected ticks; GS method showed a little higher sensitivity (11.7% ticks were positive) than DF procedure (9.4% ticks positive). Two strains of Borrelia burgdorferi were isolated from a total of 150 adult I. ricinus ticks cultured in BSK medium.     

The incidence of Alternaria spp. and Leptosphaeria maculans in commercial brassica seed in the United Kingdom

Tests on samples of oilseed rape seed ( Brassica napus ) sown in the UK between 1981 and 1984 indicated that on average 25% of samples were infected with Alternaria brassicae and 61% with Leptosphaeria maculans , with maximum incidences of infection of 19 and 4.2% respectively. Much infection by Alternaria spp. occurred on vegetable and forage brassica seed produced in the UK between 1979 and 1983. In B. oleracea types A. brassicicola occurred most frequently, affecting 88% of samples and up to 55% of seeds. A. brassicae was detected in 44% of B. oleracea samples and in up to 13% of seeds. Little Alternaria infection occurred in swede or forage rape samples (B. napus ), but A. brassicae affected up to 8–5% of seeds in turnip samples ( B. campestris ). L. maculans occurred in 44% of samples of vegetable and forage brassica seed produced in the UK, with a maximum of 4–6% infected seeds. A. brassicicola was present in 73% of samples of imported B. oleracea seed, affecting up to 25.5% of seeds. A. brassicae was absent from these samples and little L. maculans was detected. Pathogenicity tests on isolates of L. maculans from infected seeds indicated that virulent pathotypes were present in 16 rape seed samples but in only one sample (swede) of vegetable or forage brassica seed. The high incidence of seed infection by these pathogens emphasizes the importance of applying fungicide treatments to all types of brassica seed.     

Peculiarities of behaviour of taiga (Ixodes persulcatus) and sheep (Ixodes ricinus) ticks (Acarina: Ixodidae) determined by different methods

A comparison of the behavioural peculiarities of Ixodes persulcatus Schulze, 1930 (north-western population, Russia) and Ixodes ricinus (L., 1758) from western Russia and Denmark was determined by using two methods. Method 1 involved a sojourn of ticks on vertical plastic sticks and showed that the questing behaviour of I. ricinus nymphs was dependent on temperature and relative humidity (RH). A significantly greater number of nymphs quested at 22 degrees C and 100% RH than at 18 degrees C. When the humidity was reduced to 30% all of the nymphs departed. In the second method, the activity of ticks on an inclined "ticksdrome" was estimated. The activity of I. ricinus adults from the Danish population was 1.2 times greater than that of ticks from Russia. Females of the species studied and specimens from all study areas were more active than all other stages of development. The locomotor activity of both adult and immature I. ricinus that were infected with Borrelia burgdorferi sensu lato was suppressed when compared with uninfected specimens. The locomotor activity of I. persulcatus females infected by borreliae with exoskeleton anomalies was 1.3 times greater (P<0.05) than that of infected ticks without anomalies. Our data showed that infected females with exoskeleton anomalies could crawl faster on a human and reach uncovered parts of the body that are vulnerable for attachment and feeding. A study of locomotor activity and questing behaviour may be useful for comparing the risk for different tick species and populations to transmit tick-borne pathogens.     

番茄黄化曲叶病毒与番茄褪绿病毒复合侵染对番茄黄化曲叶病毒传播的影响

番茄黄化曲叶病毒(tomato yellow leaf curl virus, TYLCV)是一种由烟粉虱传播的单链环状DNA病毒, 在田间可与多种病毒发生复合侵染, 如番茄褪绿病毒(tomato chlorosis virus, ToCV)等?本文对比了TYLCV单独侵染和TYLCV与ToCV复合侵染对烟粉虱获取和传播TYLCV的影响?结果表明, 与取食TYLCV单独侵染的番茄相比, 取食复合侵染番茄的烟粉虱对TYLCV的传毒率显著提高, 且番茄植株和烟粉虱体内TYLCV的病毒积累量也显著提高?试验结果说明复合侵染会提高烟粉虱的传毒率, 促进TYLCV的发生与流行?     

Correlation between field disease and latent infection by Glomerella cingulata of strawberry plants as revealed by a simple diagnostic method using ethanol immersion

Leaves of strawberry plants growing in fields were collected and assayed by ethanol immersion treatment (SDEI) to detect latent infection by Glomerella cingulata and Dendrophoma obscurans. SDEI revealed that 83% of the plants in growers fields were latently infected by G. cingulata and 58% by D. obscurans. In such fields, only 0.8%–2.5% of the plants later became wilted or died because of G. cingulata. When the latently infected plants from naturally infested fields were kept under optimal conditions for disease development for 5 weeks, 70.0%–83.3% of them wilted or died from G. cingulata. However, only 5.6%–6.7% of the plants diagnosed by SDEI as being without latent infection wilted or died. The results indicate the importance of selecting healthy plants, suggesting that SDEI is an effective method for detecting latent infection and reducing losses from G. cingulata.     

Influence of thymic preparations on the result of experimental infection with Taenia crassiceps (Zeder, 1800) in ICR mice

Thymalin (Thymarin) and T-activin--thymic preparations of polypeptidic character--were used for influencing the parasitic infection in a model system mouse--Taenia crassiceps. A single subcutaneous application of 100 micrograms of Thymalin per mouse at the day of infection resulted in a decrease (by 54.9%) in the number of cysticerci in peritoneal cavity of experimental mice compared with the controls. Administration of Thymalin with T. crassiceps larval homogenate at various intervals before and after infection resulted in a statistically significant increase of the level of specific antibodies in the serum of infected mice, this increase, however, did not correlate with the corresponding protective effect. Immunosuppressant azathioprine, injected subcutaneously from 7th to 3rd day preceding infection at a dose of 100 micrograms resulted in a significant increase in the number of T. crassiceps larvae in the peritoneal cavity of experimental mice compared with the controls (by 48.7%). T-activin, injected subcutaneously to mice, immunosuppressed by azathioprine, led to a restoration of resistance of mice to T. crassiceps infection. Subcutaneous application of T-activin alone had a significant protective effect (decrease in cysticerci number by 53.7% in comparison with the controls). Correlation of the level of specific antibodies in the serum of infected mice, value of spleen index and number of T. crassiceps cysticerci in peritoneal cavity of mice was not detected.     

Attenuation of Schistosoma mansoni cercarial infectivity to albino mice by methanol extract of some plant species

This study elucidates the activity of certain plants’ methanol extract: Anagallis arvensis, Solanum nigrum (green fruits), Chenopodium ambrosioides, Calendula officinalis and Sesbania sesban, on the infectivity of S. mansoni cercariae to albino mice. Then, some parasitological parameters, e.g. the worm load/mouse, number of ova/g tissue in liver and intestine and the developmental stages of ova in the small intestinal wall (Oogram) of infected mice were determined. In addition, certain biochemical parameters of serum from infected mice (total protein, albumin, the activities of AlT, AsT, AcP and AkP enzymes) were, also, recorded.The results showed that exposure of S. mansoni cercariae for 30 min to the tested plants’ methanol extract before mice infection has a higher suppressive effect on their infectivity to albino mice then those exposed to this extract during mice infection. The number of worms recovered/infected mouse and the number of ova/g tissue from liver and intestine of mice groups infected with cercariae exposed to the tested plants’ methanol extract either pre- or during mice infection were less than those of infected control groups (e.g. the reduction rates of worm load/mouse and number of ova/g tissue in the intestine were 46.1% and 76.8%, respectively, for mice infected with cercariae exposed to 5 ppm of A. arvensis during mice infection).The results, also, indicated that exposing S. mansoni cercariae to methanol extract of the experimental plants either pre- or during mice infection reduced the activities of the enzymes AlT, AsT, AcP and AkP that were elevated in mice infected with untreated cercariae, meanwhile, the concentrations of total protein and albumin were increased in the serum of mice infected with these treated cercariae in comparison with those of mice group infected with untreated cercariae.     

Experimental infection of immunocompetent and immunodeficient mice with Encephalitozoon cuniculi

An experimental infection with the microsporidian Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 was studied using a model of immunocompetent BALB/c mice and immunodeficient SCID mice. The course of infection after intraperitoneal inoculation of E. cuniculi spores was evaluated using the presence of spores in peritoneal macrophages as a criterion. First significant decrease in the proportion of infected cells was recorded on day 9 post infection (p.i.) in BALB/c mice. From day 14 p.i. no spores were observed in macrophages from BALB/c mice, while the number of infected macrophages from SCID mice increased until the death of the mice. The natural killer (NK) cell activity of mouse splenocytes was compared with the production of interferon gamma (IFN-gamma) by these cells. While in BALB/c mice NK activity peaked on days 9 and 14 p.i., in SCID mice the marked increase of NK activity was recorded close before death of mice, on day 21 p.i. in correlation with the production of IFN-gamma. Production of specific antibodies was demonstrated from day 9 p.i. in sera from BALB/c mice. It is concluded that intraperitoneal infection of SCID mice with spores of E. cuniculi results in the marked increase in the number of peritoneal exudate cells and in the percentage of infected cells close before death of mice. Neither high activity of NK cells nor increased production of IFN-gamma are sufficient for the recovery of SCID mice from an E. cuniculi infection.     

烟粉虱取食感染TYLCV番茄对其解毒酶和保护酶活性的影响

为了明确感染番茄黄化曲叶病毒(Tomato yellow leaf curl virus,TYLCV)的番茄对烟粉虱生理防御的影响,本文采用生化分析法研究了烟粉虱取食感染TYLCV的番茄植株后解毒酶和保护酶活性的变化。结果表明,B型烟粉虱在带毒番茄上取食72h及30d(长期饲养种群)后,其谷胱甘肽S-转移酶(GSTs)和羧酸酯酶(CarE)活性呈现先升高后下降的趋势,而P450酶活性则持续上升,取食30d种群是对照种群的1.99倍;三大保护酶系超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)则在取食72h后,酶活性高于对照,而在感染TYLCV番茄上取食30d后,保护酶活性则持续高于72h及对照处理,分别是对照种群的1.45倍、8.42倍和5.03倍,差异显著;Q型烟粉虱表现趋势与B型烟粉虱相似。研究结果为进一步明确入侵烟粉虱与双生病毒之间的互作、揭示烟粉虱的适应性机制等补充了资料。     

饥饿胁迫对异色瓢虫幼虫发育的影响

异色瓢虫Harmonia axyridis(Pallas)幼虫在野外常遭遇间歇性食物短缺问题,为揭示食物缺乏对异色瓢虫发育的影响,以耐饥能力最强的4龄幼虫为研究对象,以禾谷缢管蚜Rhopalosiphum padi(Linnaeus)为食物,观察和分析饥饿处理(持续饲喂时间不同)和幼虫初始体重对幼虫存活、历期、成虫体型大小和寿命等发育指标的影响。结果表明,在"不饲喂"和"饲喂1 d"的饥饿胁迫处理下,4龄幼虫均不能存活至化蛹;在"饲喂2 d"的处理下,幼虫化蛹率随其初始体重增大而增大,但在"饲喂3 d"和"饲喂4 d"的处理下,幼虫化蛹率不受初始体重的影响,均为100%。饥饿处理和幼虫初始体重均显著影响4龄幼虫历期,"饲喂3 d"和"饲喂4 d"的幼虫历期与"饲喂2 d"的处理相比分别缩短58%和30%;而且在"饲喂2 d"和"饲喂3 d"处理下幼虫历期表现出随其初始体重增大而缩短的趋势。饥饿处理显著影响成虫的体重,但幼虫初始体重没有显著影响;与"饲喂2 d"的处理相比,"饲喂3 d"的成虫体重增大63.7%,"饲喂4 d"的成虫体重增大72.5%。幼虫初始体重不显著影响成虫寿命;但与"饲喂2 d"的饥饿处理相比,"饲喂4 d"的成虫寿命增大27.5%。研究结果表明,4龄幼虫需要取食足量蚜虫2 d以上方可完成发育至化蛹和羽化。     

Effect of T-activin on the course of experimental infection with Taenia crassiceps (Zeder, 1800) in mice

T-activin--an immunomodulating preparation of polypeptidic character prepared from calf thymus--was used for influencing the course of infection in a model system mouse-Taenia crassiceps. A single s.c. application of 100 micrograms of T-activin at various intervals before and after infection resulted in a marked decrease in the number of cysticerci in peritoneal cavities of experimental mice (by 47.1-93.6%) compared to the controls. After s.c. application of T-activin and i.p. injection of antigen (crude T. crassiceps larvae homogenate from mice) the decrease in the cystricercus number was still more pronounced than in the mouse groups receiving only T-activin or homogenate (by 76.9% in comparison with 65.5% and 17.0%, respectively). A combination of T-activin with crude T. crassiceps homogenate from rats did not produce the same effect in experimental mice. The protective effect of individual combinations of T-activin with the homogenate does not correlate with the antibody level in the serum of infected mice.     

Effect of vitamins on Trichinella spiralis Owen, 1835 infection in mice

The effects of vitamins A, B complex, E, and ADE on the body weight, eosinophilia, intensity of infection and distribution of T. spiralis larvae were studied in mice. The greatest loss of weight followed after the application of vitamins B complex and E. An increased eosinophilia appeared in the majority of infected mice since day 7 p.i., reaching the maximum on day 21 p.i. In mice receiving vitamins B complex, A, and ADE, the increased eosinophilia was observed still on day 60 p.i. The highest levels of eosinophilia occurred after the application of vitamins B complex and E, which was directly proportional to the intensity of infection. The lowest intensity of infection was recorded in mice receiving vitamin A. Though there were great differences between individual mice, the greatest number of larvae were localized in the diaphragm and left masseter.     

Sensitivity of Red Delicious Apple Fruit at Various Phenologic Stages to Infection by Alternaria alternata and Moldy-core Control

The fungus Alternaria alternata, is considered to be the predominant fungus involved in moldy-core of Red Delicious strains of apple. In this paper, we report on the sensitivity of various phenologic stages to infection by A. alternata, and on the efficacy of various fungicides in controlling moldy-core disease in apple orchards. Artificial inoculations conducted in the orchard during 1999 and 2000 seasons revealed that the beginning of bloom (10–30%) and full bloom were the most susceptible developmental stages for infection. Natural infection with A. alternata in fruits was relatively high, reaching 44% and 46% of the fruits on control non-treated trees in 1999 and 2000. Four foliar applications of polyoxin B, difenoconazole and azoxystrobin, starting from the beginning of bloom until fruit set, reduced the number of infected fruits by 54–70%, 61–70% and 50–65%, respectively, compared with non-treated trees. Four or eight foliar applications of each fungicide provided similar levels of control. There were no significant differences between two, four or six foliar applications of difenoconazole, neither between two or four applications of polyoxin B. Adding CaCl₂, as a tank mixture with difenoconazole at full rate, did not improve efficacy. Alternaria was recovered from the inner part of the core region of 71–88% of the fruits of the non-treated control, but was recovered less frequently from the outside part of the core region. Fruits of difenoconazole and polyoxin B treated trees were less colonized with A. alternata at both the inner and outside parts of the core region, as compared with controls. Results indicate that a control programme based on spray applications of difenoconazole or polyoxin B, during bloom period, can effectively reduce Alternaria on Red Delicious.     

棉铃虫核型多角体病毒对宿主昆虫的弱化作用

棉铃虫核型多角体病毒（ＨａＮＰＶ）感染２龄幼虫,感染３ｄ,幼虫体长和体重明显小于对照幼虫。病毒感染４龄幼虫,残留活虫幼虫历期延长,但取食量减少３７．５２％。病毒感染５龄幼虫,感染幼虫蜕皮时间延迟１８ｈ,幼虫历期延长２ｄ。幼虫血淋巴蛋白电泳结果表明,幼虫蜕皮时间延迟主要原因是蜕皮过程延长。病毒感染５龄初幼虫,残留活虫蛹重减轻１４．１９％,成虫产卵量减少２０．５８％。结果表明,ＨａＮ－ＰＶ感染棉铃虫幼     

Spontaneous infection of white laboratory mice with Emmonsia crescens Emmons et Jellison, 1960 under natural conditions

Fifty white laboratory mice were planted in a microbiotope in which adiaspiromycosis has been detected in 52 Microtus arvalis during the last 10 years. Four of the white mice became infected with adiaspiromycosis. Serological tests revealed the infection in two mice exposed for 3 months. After 4 months' exposure, another two mice were found to be infected and the positive serological results were confirmed by microscopical examination which revealed adiaspores in their lungs. The infection was thus detected by serological methods sooner than by microscopical examination.